A resolved CFD-DEM coupling method to simulate proppant transport in narrow rough fractures

A proppant transport model was proposed to simulate the fluid-granular interactions in rough narrow fractures. The Computational Fluid Dynamic (CFD) was used to describe the fluid flow, while the Discrete Element Method (DEM) was adopted to describe the particle motion. Considering the roughness characteristics of narrow fractures, the resolved CFD-DEM coupling method was employed to simulate the fluid-granular interactions. Firstly, the resolved CFD-DEM coupling method was validated by previous simulation/experimental results. Then, simulations of proppant transport in synthetic rough fractures with different fractal dimensions and random number seeds were conducted. The results showed that roughness characteristics increased the possibility of proppant settling at a location with a large roughness height. A fracture with a higher fractal dimension had a higher proppant coverage ratio, leading to a better fracture propping effect. The proppant coverage ratio in rough fractures increased with increasing proppant size and decreasing injection rate.